Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Examples of natural image stimuli. The natural images used in the experiment were sampled from a large database of images obtained from a commercial digital library (Corel Stock Photo Libraries from Corel Corporation). The images covered 20× 20 degrees of the field of view, and were cropped to a circular aperture and blended into the background to reduce edge effects.
